1. Field of the Invention
The present invention relates generally to tool holders. Particularly, the present invention relates to holders for sharpening and faceting. More particularly, the present invention relates to honing guides and tool grinding rests.
2. Description of the Prior Art
The traditional method of faceting gemstones and/or glass includes first mounting a gem crystal on a metal dowel, (i.e. “dop” or “dopstick’). The dop fits into one end of a quill. The opposite end of the quill is pivotably attached to a vertical mast mounted near the edge of a horizontal, rotating abrasive disk. The user adjusts the height of the quill to achieve the desired angle with respect to the abrasive disk. The user then touches the gem crystal to the rotating abrasive disk to create facets in the gem crystal. The user facets the crown of the stone first, followed by the pavilion. Due to lockable pre-determined settings of height, angle, and index, the desired facets are cut/formed into the stone.
The height determines the depth to which a facet is cut, enabling the user to create even, uniform rows of facets of the same size and depth. The angle determines the plane of each facet cut in the stone. The index determines placement of the facets around the stone and enables the user to cut facets that result in the overall shape and appearance of the stone, such as round brilliant cut or emerald cut. The placement and angle of the facets determine the brilliance of the stone due to optical properties and reflection of light through the stone.
The steps applied to faceting gemstones can also be applied to other objects. A simple form of faceting is the act of sharpening a single cutting edge of a tool. In such faceting operations, which are more commonly referred to as sharpening or honing, it is common to use jigs to hold the tool at a predetermined angle to a grind stone. Typically, the grind stones are water cooled. The grinding jigs usually include a roller that supports a plate upon which the tool is secured. The support plate holds the tool at a selected angle against the stone surface. As the stone is moved, the cutting edge is ground or honed at the selected angle. The initial setting of the tool in the jig was critical to the success of the operation.
The present use of such guides is now customarily limited to flat bench stones. The skilled artisan, however, differentiates between grinding and honing. Grinding is considered as defining the basic edge and honing considered as refining the basic edge to the finished sharp edge. In the normal sharpening process, the edge to be sharpened is initially passed over the coarse stone at a selected angle. This process leaves a ragged edge of the desired angle. The bevel is then refined over a stone of finer particles. Since such stones cut more slowly, the work is done on the part of the bevel which intersects with the face of the tool to provide a micro-bevel.
The micro-bevel selected should be a function of the tool material, the material to be cut and the intended use. Ideally, the bevel angle should be no greater than is necessary to prevent the edge from breaking down so that the wedging action of the tool is minimized as the edge enters the material to be cut.
When manually sharpening a tool's cutting edge, the skilled artisan uses a variety of methods that include oil stones, water stones, sandpaper, loose grit or paste on glass, etc. Honing stones typically have a rectangular shape. When using an oil stone, a small amount of lightweight honing oil is usually placed on the honing stone. The skilled artisan then pulls or pushes the cutting edge over the honing stone at the desired angle as if the cutting edge were scrapping the surface of the honing stone, i.e. the cutting edge is pushed or pulled over the honing surface in a perpendicular fashion to the cutting edge. Several blade holders have been devised that facilitate manual sharpening of a cutting edge over a honing surface.
U.S. Pat. No. 4,733,501 (1988, McLean) discloses a honing guide. The honing guide includes a tool support plate mounted above a surface-engaging roller. The surface engaging roller is mounted eccentrically so that the height of the tool support plate may be varied to provide a range of honing angles without unclamping the tool from the guide.
U.S. Pat. No. 5,472,375 (1995, Pugh) discloses a blade sharpening angle guide. The blade sharpening guide includes an elongated curved block having a longitudinal slot therethrough. The longitudinal slot releasably holds a knife blade with the blade cutting edge extending a distance outside the slot.
U.S. Pat. No. 6,030,281 (2000, Cozzini et al.) discloses a sharpening apparatus. The sharpening apparatus includes a base member on which a sharpening stone is positioned. A slidable blade guide member is slidably connected to the base member and includes a guide surface that is disposed at an angle relative to the upper surface of the sharpening stone and a mounting mechanism for removably mounting a spatula against the guide surface such that the scraping edge of the spatula is in engagement with the sharpening stone. The slidable blade guide member is manually slidable back and forth to sharpen the scraping edge of the spatula. A fixed blade guide member is also attached to the base member. The fixed blade guide member includes a horizontal slot that is adapted to receive the shaft of a grill scraper. The fixed blade guide member is adapted to provide guided back and forth sliding movement of the grill scraper within the slot and engagement with the sharpening member to sharpen the scraping edge of the grill scraper.
The above-described devices require the cutting edge of the tool to move over and against the sharpening/honing stone in a “scraping” motion. In other words, the motion of the cutting edge to the stone surface is similar to the action used with a scraper/tool. The motion of the cutting edge of the cutting tool against the honing stone surface is perpendicular to the longitudinal axis of the cutting edge.